I need to make a timeline that shows the history of gendered movements since the 1700's... I'm having a hard time finding things that happened in the 18th century.

For 18th century European gender history, you might take a look at Karen Offen's European Feminisms, 1700-1950: A Political History.

For gender in the Americas in this same early time period, a good general reference text that I have used in courses I have taught before is Sylvia Hoffert's A History of Gender in America. The sections here on the pre-revolutionary period are brief but meaningful, and every section of the book includes a list of primary source materials that could be useful to you. It also includes some very important secondary sources, like Laurel Thatcher Ulrich's pathbreaking work about colonial American women that coined the phrase: "Well-behaved women seldom make history."

Of course, you might just want to talk about individual women and their actions in the 18th century as being important things to note on your timeline (since organized gender-based political and/or social movements were few and far between). A good example of this is Abigail Adams debating with her husband John on the eve of the American Revolution to "Remember the Ladies" in correspondence she sent to him while he was representing Massachusetts at the Continental Congress in Philadelphia in the spring of 1776. You might also point to British author/feminist Mary Wollstonecraft and her publication of A Vindication of the Rights of Woman in 1792.